There is a very large, and still rapidly growing, demand for wireless communication services today. Mobile telephone services are used to a very large extent, e.g. for telephone conversations and text messages. Also, high speed wireless communication is used for a large number of applications, such as internet browsing, streaming of music, films and/or television, and the like.
Since the demand for wireless communication services is very high, and the end users expect the wireless services to be available essentially everywhere they go, the wireless communication system coverage must cover very large geographical areas, both indoors and outdoors, and also provide high bitrates in these areas.
Traditionally, radio base stations, such as Base Transceiver Stations (BTS) and/or NodeBs and/or eNodeBs, hereinafter called Remote Unit Controllers (RUC), are typically located very close to a tower comprising one or more tower-mounted antennas. Said RUCs are provided with all the circuitry necessary for sending and receiving the wireless communication signals to and from the mobile equipments connecting to it, such as Mobile Stations (MS) or User Equipments (UEs). The radio base stations have typically been arranged in cells. The traditional radio base stations include both the circuitry to receive and transmit signals from and to a core network and to receive and transmit signals from and to the one or more antennas, including radio frequency (RF) circuits and power amplifiers.
However, since the end users nowadays expect the high speed wireless communication services, such as mobile telecommunication services, wireless fidelity networks (WiFi), and Wireless Local Area Networks (WLANs), to be available essentially everywhere, it would be very costly to build traditional radio base stations at every site where coverage and high bitrates are needed. Also, in indoor locations, such as in malls, railway tunnels, road tunnels, restaurants, cafés, airports, conference centers, tunnels, stadiums and exhibition halls, the traditional radio base station concept results in poor service coverage and bitrates.
Further, such systems have to be installed, maintained, monitored and controlled. Also, each one of these systems have to be provided with power supplies, distribution networks, locations for mounting radio base stations, control units and antenna arrangements. Thus, to provide sufficient coverage and bitrates today is very costly, and it is also very work and time consuming to monitor and maintain all of these different systems.
Aim And Most Important Features Of The Invention
It is an object of the present invention to provide a more efficient and cost and space effective communication system.
Accordingly, the invention provides a first and a second interconnection unit, a system comprising said units, as well as a method in said respective units, having features set forth in the independent claims. Advantageous embodiments of the invention are defined by the dependent claims.
Hence, according to a first aspect of the present invention, a first interconnection unit is provided. The first interconnection unit comprises a first and a second communication interface, a first and a second electro-optical converter and a multiplexing unit. During operation, the first communication interface receives a first stream of electrically transmitted analog information, which is converted at the first electro-optical converter into a first stream of optically transmitted analog information. Further, the second communication interface receives a first stream of electrically transmitted digital information which is converted at the second electro-optical converter into a first stream of optically transmitted digital information. The first stream of optically transmitted analog information and the first stream of optically transmitted digital information are then multiplexed at the multiplexing unit and output over a bidirectional link.
According to a second aspect of the present invention, a second interconnection unit is provided, which comprises a first and a second communication interface, a first and a second electro-optical converter and a multiplexing unit. The first interconnection unit is adapted such that a multiplexed first stream of optically transmitted analog information and first stream of optically transmitted digital information, transmitted over a bidirectional link, is received and de-multiplexed at the multiplexing unit. The first stream of optically transmitted analog information and first stream of optically transmitted digital information are then converted at the first electro-optical converter into a first stream of electrically transmitted analog information, whereas the first stream of optically transmitted digital information is converted at the second electro-optical converter into a first stream of electrically transmitted digital information. The first stream of electrically transmitted analog information is output at the first communication interface and the first stream of electrically transmitted digital information is output at the second communication interface.
According to a third aspect of the present invention, a method in the first interconnection unit according to the first aspect is provided. In the method, a first stream of electrically transmitted analog information is received and converted into a first stream of optically transmitted analog information. Further, a first stream of electrically transmitted digital information is received and converted into a first stream of optically transmitted digital information. The converted streams of analog and digital information are then multiplexed and output over a bidirectional link.
According to a fourth aspect of the present invention, a method in the second interconnection unit according to the second aspect is provided. In the method, a multiplexed first stream of optically transmitted analog information and first stream of optically transmitted digital information transmitted over a bidirectional link is received and de-multiplexed. The first stream of optically transmitted analog information is then converted and output as a first stream of electrically transmitted analog information. The first stream of optically transmitted digital information is converted into a first stream of electrically transmitted digital information, and output.
According to a fifth aspect of the present invention, a system comprising a first interconnection unit according to the first aspect and a second interconnection unit according to the second aspect is provided, the system being adapted to perform a method according to the third and fourth aspects of the present invention.
By the term “stream of information” should be understood communication signals, or a communication link, carrying e.g. analog or digital information between a transmitting unit, such as e.g. core network, and a receiving unit, such as e.g. a mobile station or user equipment. The information may e.g. be optically or electrically transmitted between the units.
The optically transmitted information may be divided into a first and a second portion of an optical spectrum, wherein the first portion of the spectrum may be allocated for carrying analog information and the second portion allocated for carrying digital information. The first and second portions may be separated such that the first portion employs a set of frequencies not being employed by the second portion of the spectrum. The first and second portions of the spectrum may e.g. be realized by a first and a second laser of different colors.
The communication system, which also may be referred to as a distribution network, is adapted to transmit multiplexed streams of analog and digital information over the bidirectional link, which e.g. may be an existing optical fiber or be included in the communication system.
The interconnection unit and corresponding method according to the first and third aspects is advantageous in that streams of both digital and analog information can be combined and transmitted over a single link, such as a fiber. Being able to supply both analog and digital communication services over a single fiber is advantageous as the access to available fibers, which may be owned and operated by third parties, often may be scarce and/or expensive. Further, using a single first and/or second interconnection unit for transmitting streams of information over the fiber advantageously reduces the space and equipment required for mounting, service, monitoring, and power supply as compared with prior art radio base station systems The total weight of, and wind forces caused by, these units can also be reduced by the integrated implementation of the units.
By using the interconnection units and corresponding methods, the digital and analog information, which is transmitted over the bidirectional link, may advantageously be de-multiplexed and output to the respective communication services in the form of electrical signals. Thereby digital and analog services may be supplied with streams of information that have been transmitted over a common link, such as a single fiber. By integrating the multiplexing unit and the electro-optical converters in the interconnection unit the space required for mounting and installation may be reduced. Further, service, power supply and monitoring may be facilitated as compared with traditional radio bases systems.
According to embodiments, the first interconnection unit and related method may be further adapted to receive, at the multiplexing unit, a multiplexed second stream of optically transmitted analog information and second stream of optically transmitted digital information transmitted over the bidirectional link. Said received information is then de-multiplexed at the multiplexing unit and converted, at the first and second electro-optical converter, into a second stream of electrically transmitted analog and digital information, respectively.
The second stream of electrically transmitted analog information is output at the first communication interface, whereas the second stream of optically transmitted digital information is output at the second communication interface.
This also applies, mutatis mutandis, on the second interconnection unit and corresponding method, wherein a second stream of electrically transmitted analog information and a second stream of electrically transmitted digital information are received, converted, multiplexed, and output accordingly.
An interconnection unit able of both outputting and receiving multiplexed analog and digital information over the bidirectional link advantageously allows for both uplink and downlink communication. The communication over the bidirectional link may e.g. be full-duplex, wherein a first and a second stream of optically transmitted analog and/or digital information may be simultaneously transmitted in both directions, or half-duplex wherein said first and second streams of information may be transmitted in both directions, but only one direction at a time.
The system according to the fifth aspect is advantageous in that it provides a communication system capable of simultaneously supplying a wide range of both analog and digital communication services with communication signals over a single fiber. The communication system may e.g. be combined with an existing analog RF system in order to enable digital systems, such as WLANs, to be added to the architecture. Combining digital and analog systems in the same architecture, e.g. using a single first connection unit and/or a single second connection unit, is advantageous at locations having certain requirements regarding e.g. mounting space, weight, visual appearance (in terms of number of visual units), government permits, etc. By integrating both digital communication services and analog communication services in the communication system the power consumption, weight, and volume of the hardware may be reduced and hence the installation, service, and monitoring may be facilitated.
The communication system, or distribution network, and the methods for transmitting analog and/or digital streams of information, or signals, according to the present invention are based on the realization that the spectrum of the signals can be divided into at least two parts, wherein the first part of the spectrum is allocated for transmission of at least one stream of analog information, such as an RF link for a distributed antenna system (DAS), e.g. RF over fiber for an embodiment of the present invention utilizing a fiber based communication network in the DAS. Further, at least one second part of the spectrum may be allocated for transmission of at least one stream of digital information, or a digital link. This at least one digital link can e.g. be utilized for supplying digital communication signals for at least one RRH unit and/or at least one Wireless Local Area Network (WLAN) unit and/or at least one pico base station and/or at least one femto base station and/or at least one remote Ethernet unit.
Transmission of both analog RF communication for services including e.g. a DAS, and digital communication for e.g. one or more of at least one RRH unit, at least one WLAN unit, at least one pico base station, at least one femto base station and at least one remote Ethernet unit thus enabled which advantageously provides an efficient and cost effective utilization of the distribution network, or communication system. Also, an overall low cost communication system, which can supply a number of services in parallel, is provided.
According to an embodiment, the multiplexing unit may be a wavelength division unit applying wavelength division multiplexing, WDM, on the spectrum of the streams of optically transmitted analog and digital information such that each separate part of the spectrum utilizes a number of wavelengths being separate from wavelengths being utilized by other separate parts of the spectrum. Thus, the first part of the spectrum employs a first set of wavelengths and the at least one second part of the spectrum employs at least one second set of wavelengths, wherein the first and at least one second sets of wavelengths are separate from each other.
According to an embodiment of the present invention, the multiplexing units may apply frequency division multiplexing, FDM, on the spectrum of the streams of optically transmitted analog and digital information, such that each separate part of the spectrum uses a number of frequencies being separate from frequencies being used by other separate part of the spectrum. Thus, the first part of the spectrum employs a first set of frequencies and the at least one second part of the spectrum employs at least one second set of frequencies, wherein the first and at least one second sets of frequencies are separate from each other.
Also, by different embodiments of the present invention, the communication system may comprise, or be adapted to supply with signals, a DAS having one or more Remote Unit Controllers, RUC, each possibly being utilized by one operator/service provider and adapted to provide a stream of electrically transmitted analog information, such as RF signals, to the first interconnection unit which outputs the information over the bidirectional link to the second interconnection unit. The second interconnection unit may then distribute the RF signals to one or more Remote Units, RUs, which may be integrated in the second interconnection unit, and antenna arrangements being located at suitable locations for proving coverage and sufficient bitrates where the demand is.
According to embodiments of the present invention, the communication system is adapted to transmit further optical signals e.g. supplying a remote radio head unit or an Ethernet unit. The optical signals may comprise analog and/or digital information. As an example, a first optical signal may be received by the first interconnection unit and directly transmitted to the multiplexing unit, at which the first optical signal is multiplexed and transmitted over the bi-directional link together with the streams of optically transmitted analog and digital information. The multiplexed first optical signal may then be received at the second interconnection unit, de-multiplexed at the multiplexing unit and output from the second interconnection unit. The optical signal can be transmitted without passing an electro-optical converter. The communication system may also be adapted to transmit a second optical signal in the other direction, i.e. receiving the second optical signal at the second interconnection unit, at which it is multiplexed and output over the bi-directional link to the first interconnection unit, wherein the signal is de-multiplexed and output.
According to an embodiment, the communication system is adapted to utilize a Common Public Radio Interface, CPRI, communication protocol and/or an Open Base Station Architecture Initiative (OBSAI) communication protocol during transmission of the first and/or second optical signal(s).
According to embodiments of the present invention, at least one or more in the group of: a RRH unit, a WLAN unit; a pico base station; a femto base station; a remote Ethernet unit; or a combination thereof, may be integrated in a RU of the DAS.
This has a number of integration advantages regarding e.g. network costs, mounting costs and power supplies. The total weight of, and wind forces caused by, these units can also be reduced by the integrated implementation of the units in the DAS RUs.
According to an embodiment of the present invention, the first part of the signal spectrum may convey analog RF signals for the one or more RUs of the DAS and the second part of the spectrum may convey digital RRH communication signals for the RRH units.
According to an embodiment of the present invention, the first part of the signal spectrum may convey RF DAS signals for the one or more DAS RUs and the second part of the spectrum WiFi/WLAN communication signals. The analog DAS RF signals and the digital WiFi/WLAN communication signals may be diplexed and transmitted over the distribution network.
The invention may be embodied as computer-readable instructions for controlling a programmable computer in such manner that it performs the method according to the third and fourth aspects outlined above. Such instructions may be distributed in the form of a computer-program product comprising a computer-readable medium storing the instructions.
Further objectives of, features of and advantages with the present invention will be apparent when studying the following detailed disclosure, the drawings and the appended claims. Those skilled in the art realize that different features of the present invention, even if recited in different claims, can be combined in embodiments other than those described in the following.